Merge tag 'trace-v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Add missing LOCKDOWN checks for eventfs callers

   When LOCKDOWN is active for tracing, it causes inconsistent state
   when some functions succeed and others fail.

 - Use dput() to free the top level eventfs descriptor

   There was a race between accesses and freeing it.

 - Fix a long standing bug that eventfs exposed due to changing timings
   by dynamically creating files. That is, If a event file is opened for
   an instance, there's nothing preventing the instance from being
   removed which will make accessing the files cause use-after-free
   bugs.

 - Fix a ring buffer race that happens when iterating over the ring
   buffer while writers are active. Check to make sure not to read the
   event meta data if it's beyond the end of the ring buffer sub buffer.

 - Fix the print trigger that disappeared because the test to create it
   was looking for the event dir field being filled, but now it has the
   "ef" field filled for the eventfs structure.

 - Remove the unused "dir" field from the event structure.

 - Fix the order of the trace_dynamic_info as it had it backwards for
   the offset and len fields for which one was for which endianess.

 - Fix NULL pointer dereference with eventfs_remove_rec()

   If an allocation fails in one of the eventfs_add_*() functions, the
   caller of it in event_subsystem_dir() or event_create_dir() assigns
   the result to the structure. But it's assigning the ERR_PTR and not
   NULL. This was passed to eventfs_remove_rec() which expects either a
   good pointer or a NULL, not ERR_PTR. The fix is to not assign the
   ERR_PTR to the structure, but to keep it NULL on error.

 - Fix list_for_each_rcu() to use list_for_each_srcu() in
   dcache_dir_open_wrapper(). One iteration of the code used RCU but
   because it had to call sleepable code, it had to be changed to use
   SRCU, but one of the iterations was missed.

 - Fix synthetic event print function to use "as_u64" instead of passing
   in a pointer to the union. To fix big/little endian issues, the u64
   that represented several types was turned into a union to define the
   types properly.

* tag 'trace-v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  eventfs: Fix the NULL pointer dereference bug in eventfs_remove_rec()
  tracefs/eventfs: Use list_for_each_srcu() in dcache_dir_open_wrapper()
  tracing/synthetic: Print out u64 values properly
  tracing/synthetic: Fix order of struct trace_dynamic_info
  selftests/ftrace: Fix dependencies for some of the synthetic event tests
  tracing: Remove unused trace_event_file dir field
  tracing: Use the new eventfs descriptor for print trigger
  ring-buffer: Do not attempt to read past "commit"
  tracefs/eventfs: Free top level files on removal
  ring-buffer: Avoid softlockup in ring_buffer_resize()
  tracing: Have event inject files inc the trace array ref count
  tracing: Have option files inc the trace array ref count
  tracing: Have current_trace inc the trace array ref count
  tracing: Have tracing_max_latency inc the trace array ref count
  tracing: Increase trace array ref count on enable and filter files
  tracefs/eventfs: Use dput to free the toplevel events directory
  tracefs/eventfs: Add missing lockdown checks
  tracefs: Add missing lockdown check to tracefs_create_dir()

6 files changed, 88 insertions, 30 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 78502d4c7214..a1651edc48d5 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2198,6 +2198,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
 				err = -ENOMEM;
 				goto out_err;
 			}
+
+			cond_resched();
 		}
 
 		cpus_read_lock();
@@ -2388,6 +2390,11 @@ rb_iter_head_event(struct ring_buffer_iter *iter)
 	 */
 	commit = rb_page_commit(iter_head_page);
 	smp_rmb();
+
+	/* An event needs to be at least 8 bytes in size */
+	if (iter->head > commit - 8)
+		goto reset;
+
 	event = __rb_page_index(iter_head_page, iter->head);
 	length = rb_event_length(event);
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2b4ded753367..abaaf516fcae 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1772,7 +1772,7 @@ static void trace_create_maxlat_file(struct trace_array *tr,
 	init_irq_work(&tr->fsnotify_irqwork, latency_fsnotify_workfn_irq);
 	tr->d_max_latency = trace_create_file("tracing_max_latency",
 					      TRACE_MODE_WRITE,
-					      d_tracer, &tr->max_latency,
+					      d_tracer, tr,
 					      &tracing_max_lat_fops);
 }
 
@@ -1805,7 +1805,7 @@ void latency_fsnotify(struct trace_array *tr)
 
 #define trace_create_maxlat_file(tr, d_tracer)				\
 	trace_create_file("tracing_max_latency", TRACE_MODE_WRITE,	\
-			  d_tracer, &tr->max_latency, &tracing_max_lat_fops)
+			  d_tracer, tr, &tracing_max_lat_fops)
 
 #endif
 
@@ -4973,6 +4973,33 @@ int tracing_open_generic_tr(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+/*
+ * The private pointer of the inode is the trace_event_file.
+ * Update the tr ref count associated to it.
+ */
+int tracing_open_file_tr(struct inode *inode, struct file *filp)
+{
+	struct trace_event_file *file = inode->i_private;
+	int ret;
+
+	ret = tracing_check_open_get_tr(file->tr);
+	if (ret)
+		return ret;
+
+	filp->private_data = inode->i_private;
+
+	return 0;
+}
+
+int tracing_release_file_tr(struct inode *inode, struct file *filp)
+{
+	struct trace_event_file *file = inode->i_private;
+
+	trace_array_put(file->tr);
+
+	return 0;
+}
+
 static int tracing_mark_open(struct inode *inode, struct file *filp)
 {
 	stream_open(inode, filp);
@@ -6691,14 +6718,18 @@ static ssize_t
 tracing_max_lat_read(struct file *filp, char __user *ubuf,
 		     size_t cnt, loff_t *ppos)
 {
-	return tracing_nsecs_read(filp->private_data, ubuf, cnt, ppos);
+	struct trace_array *tr = filp->private_data;
+
+	return tracing_nsecs_read(&tr->max_latency, ubuf, cnt, ppos);
 }
 
 static ssize_t
 tracing_max_lat_write(struct file *filp, const char __user *ubuf,
 		      size_t cnt, loff_t *ppos)
 {
-	return tracing_nsecs_write(filp->private_data, ubuf, cnt, ppos);
+	struct trace_array *tr = filp->private_data;
+
+	return tracing_nsecs_write(&tr->max_latency, ubuf, cnt, ppos);
 }
 
 #endif
@@ -7752,18 +7783,20 @@ static const struct file_operations tracing_thresh_fops = {
 
 #ifdef CONFIG_TRACER_MAX_TRACE
 static const struct file_operations tracing_max_lat_fops = {
-	.open		= tracing_open_generic,
+	.open		= tracing_open_generic_tr,
 	.read		= tracing_max_lat_read,
 	.write		= tracing_max_lat_write,
 	.llseek		= generic_file_llseek,
+	.release	= tracing_release_generic_tr,
 };
 #endif
 
 static const struct file_operations set_tracer_fops = {
-	.open		= tracing_open_generic,
+	.open		= tracing_open_generic_tr,
 	.read		= tracing_set_trace_read,
 	.write		= tracing_set_trace_write,
 	.llseek		= generic_file_llseek,
+	.release	= tracing_release_generic_tr,
 };
 
 static const struct file_operations tracing_pipe_fops = {
@@ -8956,12 +8989,33 @@ trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
 	return cnt;
 }
 
+static int tracing_open_options(struct inode *inode, struct file *filp)
+{
+	struct trace_option_dentry *topt = inode->i_private;
+	int ret;
+
+	ret = tracing_check_open_get_tr(topt->tr);
+	if (ret)
+		return ret;
+
+	filp->private_data = inode->i_private;
+	return 0;
+}
+
+static int tracing_release_options(struct inode *inode, struct file *file)
+{
+	struct trace_option_dentry *topt = file->private_data;
+
+	trace_array_put(topt->tr);
+	return 0;
+}
 
 static const struct file_operations trace_options_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_options,
 	.read = trace_options_read,
 	.write = trace_options_write,
 	.llseek	= generic_file_llseek,
+	.release = tracing_release_options,
 };
 
 /*
@@ -9739,8 +9793,8 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 			  tr, &tracing_mark_fops);
 
 	file = __find_event_file(tr, "ftrace", "print");
-	if (file && file->dir)
-		trace_create_file("trigger", TRACE_MODE_WRITE, file->dir,
+	if (file && file->ef)
+		eventfs_add_file("trigger", TRACE_MODE_WRITE, file->ef,
 				  file, &event_trigger_fops);
 	tr->trace_marker_file = file;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 5669dd1f90d9..77debe53f07c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -610,6 +610,8 @@ void tracing_reset_all_online_cpus(void);
 void tracing_reset_all_online_cpus_unlocked(void);
 int tracing_open_generic(struct inode *inode, struct file *filp);
 int tracing_open_generic_tr(struct inode *inode, struct file *filp);
+int tracing_open_file_tr(struct inode *inode, struct file *filp);
+int tracing_release_file_tr(struct inode *inode, struct file *filp);
 bool tracing_is_disabled(void);
 bool tracer_tracing_is_on(struct trace_array *tr);
 void tracer_tracing_on(struct trace_array *tr);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ed367d713be0..91951d038ba4 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -992,19 +992,6 @@ static void remove_subsystem(struct trace_subsystem_dir *dir)
 
 static void remove_event_file_dir(struct trace_event_file *file)
 {
-	struct dentry *dir = file->dir;
-	struct dentry *child;
-
-	if (dir) {
-		spin_lock(&dir->d_lock);	/* probably unneeded */
-		list_for_each_entry(child, &dir->d_subdirs, d_child) {
-			if (d_really_is_positive(child))	/* probably unneeded */
-				d_inode(child)->i_private = NULL;
-		}
-		spin_unlock(&dir->d_lock);
-
-		tracefs_remove(dir);
-	}
 	eventfs_remove(file->ef);
 	list_del(&file->list);
 	remove_subsystem(file->system);
@@ -2103,9 +2090,10 @@ static const struct file_operations ftrace_set_event_notrace_pid_fops = {
 };
 
 static const struct file_operations ftrace_enable_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_file_tr,
 	.read = event_enable_read,
 	.write = event_enable_write,
+	.release = tracing_release_file_tr,
 	.llseek = default_llseek,
 };
 
@@ -2122,9 +2110,10 @@ static const struct file_operations ftrace_event_id_fops = {
 };
 
 static const struct file_operations ftrace_event_filter_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_file_tr,
 	.read = event_filter_read,
 	.write = event_filter_write,
+	.release = tracing_release_file_tr,
 	.llseek = default_llseek,
 };
 
@@ -2297,6 +2286,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
 {
 	struct event_subsystem *system, *iter;
 	struct trace_subsystem_dir *dir;
+	struct eventfs_file *ef;
 	int res;
 
 	/* First see if we did not already create this dir */
@@ -2329,13 +2319,14 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
 	} else
 		__get_system(system);
 
-	dir->ef = eventfs_add_subsystem_dir(name, parent);
-	if (IS_ERR(dir->ef)) {
+	ef = eventfs_add_subsystem_dir(name, parent);
+	if (IS_ERR(ef)) {
 		pr_warn("Failed to create system directory %s\n", name);
 		__put_system(system);
 		goto out_free;
 	}
 
+	dir->ef = ef;
 	dir->tr = tr;
 	dir->ref_count = 1;
 	dir->nr_events = 1;
@@ -2415,6 +2406,7 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
 	struct trace_event_call *call = file->event_call;
 	struct eventfs_file *ef_subsystem = NULL;
 	struct trace_array *tr = file->tr;
+	struct eventfs_file *ef;
 	const char *name;
 	int ret;
 
@@ -2431,12 +2423,14 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
 		return -ENOMEM;
 
 	name = trace_event_name(call);
-	file->ef = eventfs_add_dir(name, ef_subsystem);
-	if (IS_ERR(file->ef)) {
+	ef = eventfs_add_dir(name, ef_subsystem);
+	if (IS_ERR(ef)) {
 		pr_warn("Could not create tracefs '%s' directory\n", name);
 		return -1;
 	}
 
+	file->ef = ef;
+
 	if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
 		eventfs_add_file("enable", TRACE_MODE_WRITE, file->ef, file,
 				  &ftrace_enable_fops);
diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c
index abe805d471eb..8650562bdaa9 100644
--- a/kernel/trace/trace_events_inject.c
+++ b/kernel/trace/trace_events_inject.c
@@ -328,7 +328,8 @@ event_inject_read(struct file *file, char __user *buf, size_t size,
 }
 
 const struct file_operations event_inject_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_file_tr,
 	.read = event_inject_read,
 	.write = event_inject_write,
+	.release = tracing_release_file_tr,
 };
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 9897d0bfcab7..14cb275a0bab 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -337,7 +337,7 @@ static void print_synth_event_num_val(struct trace_seq *s,
 		break;
 
 	default:
-		trace_seq_printf(s, print_fmt, name, val, space);
+		trace_seq_printf(s, print_fmt, name, val->as_u64, space);
 		break;
 	}
 }